The great potential for use of biomasses for the production of ethanol is being demonstrated worldwide year after year, with the use of various technological configurations and based on the use of a substantially wide variety of biomass types, to wit: C4 plants—belonging to the genera Lolium, Spartina, Panicum, Miscanthus, and combinations thereof; sugarcane bagasse (originating from a grinding mill and/or diffuser), sugarcane straw (originating from the sugarcane harvesting process, either manual or mechanized); straw of cereals such as wheat, rice, rye, barley, oats, corn and similar materials (e.g., Napier grass—“switchgrass”); wood; stalks and stems of banana plants, cactaceae, paperboard, sawdust, newspapers; agro-industrial or municipal waste materials and combinations thereof.
In Brazil, the sugarcane business dates back to the colonization of the country (1532), this being the year when the first seedlings were introduced to the region. However, for more than 500 years to date, Brazil only uses one third of the energy that can be derived from the sugarcane—the juice—for manufacturing sugar and alcohol. Thus, it is possible to consider an increase in productivity and cost reduction in the bioenergy chain, not only by way of gradual progress of the technologies currently in use, but also through the advent of new technologies, such as the case of technologies for the production of second generation ethanol, that will allow large-scale utilization of the remaining two-thirds of the plant (the biomass comprised of bagasse and straw).
These materials—sugarcane bagasse and straw—represent the most appropriate biomasses for the production of ethanol from lignocellulosic sources in our country, not only due to comprising between 40% and 50% cellulose, but also due to the significant volume of those byproducts generated as derivatives in the production of sugar and 1G ethanol. In this scenario, the development of a process for the production of 2G ethanol that mainly takes into account the aspects of thermal and infrastructural integration with the production of 1G ethanol seems to constitute the most feasible option.
The instant application therefore refers to a system and a method that enable the installation of a plant (technology) for the production of second generation ethanol annexed to a conventional first generation ethanol plant (irrespective of the raw material that is processed), considering the integral use of the biomass, that is to say, of sugars obtained from the extraction of the juice and the carbohydrates present in the residue having been generated (fibers). This strategy allows the enhancement of the production capacity of sugar and alcohol production plants and also of autonomous distilleries spread worldwide, by way of the recovery of streams and/or effluents currently available in plants that are presently in operation, preserving the formerly existing energy self-sufficiency, by means of the concept of process integration. This concept is mainly intended to optimize the use of energy and to reduce the environmental impact caused by industrial processes. Thus, one object of the present invention consists in the provision of a process for joint (integrated) production of 1G/2G ethanol, comprising the recovery of streams and effluents generated in the 1G process, towards supplying a significant parcel of the energy required for operating the 2G plant.
The technology for the production of second generation (2G) ethanol in Brazil is still undergoing a maturing period, and at present it still does not have plants already installed and with relevant capacity for commercial scale production. This scenario implies an excellent opportunity for implementation of the objectives described in the instant application, due to the same being able to afford significant gains with relation to the recovery of energy and effluents.
The documents cited in the following constitute references to the prior art relative to schemes of energy utilization and reuse of process streams, however none of these schemes either anticipates or suggests the subject matter disclosed in the present invention.
The doctorate thesis with the title “Modelagem e integração energetica do processo de produção de etanol a partir de biomassa de cana-de-açúcar” [Modeling and energy integration of the process of production of ethanol from sugarcane biomass] (Bereche, R. P., presented at the School of Mechanical Engineering of the UNICAMP university [University of Campinas, State of São Paulo, Brazil] in Jul. 21, 2011) discloses a theoretical analysis of the existing individual operations in a sugarcane and alcohol (1G) processing plant (1G), in addition to possible technologies for the production of cellulose-derived ethanol (2G). In the thesis in question, the author cites the possibility of promoting energy integration between the 1G and 2G technologies, however restricting the scope of applicability thereof to the use of sugarcane bagasse for the production of 2G-ethanol and to the juice evaporation system as an alternative for energy integration of the processes mentioned above. The process for joint (integrated) production of 1G/2G ethanol as disclosed in the instant patent application differs from the mentioned doctorate thesis on disclosing as constituting sources of raw materials for the obtainment of 2G ethanol all residue derived from the harvest of sugarcane and/or other crops (lignocellulosic materials), in addition to presenting practical and feasible solutions for optimizing the consumption of process water and for the reuse of effluents within the industrial environment, entailing important environmental benefits. Thus, the thesis under consideration does not anticipate the state of the art that is disclosed in the present document.
The master's thesis with the title “Integração das Principals Tecnologias de Obtenção de Etanol Através do Processamento da Celulose (2a Geracao) nas atuais usinas de cana-de-açúcar (1a Geração)” [Integration of the Main Technologies for Obtainment of Ethanol By Means of Processing of Cellulose (2nd Generation) in current sugarcane processing plants (1st Generation)] (Bernardo Neto, O., presented at the Polytechnics School of the University of São Paulo in Mar. 25, 2009) discloses a bibliographic review regarding the various second generation technologies and proposes the process of gasification of surplus biomass as constituting the best alternative for enhancing the energy efficiency of a sugarcane processing plant. Thus, the mentioned dissertation differs from the instant application due to failing to anticipate or suggest the use of process streams and effluents to optimize the energy integration of the processes for production of 1G+2G ethanol.
The article bearing the title “Production of bioethanol and other bio-based materials from sugarcane bagasse: Integration to conventional bioethanol production process” (Dias et al., Chemical Engineering Research and Design, 2009, 87: 1206-1216) discloses a study on thermal integration in the distillery by way of the technique of double effect distillation, associated to the ORGANOSOLV technology for acid hydrolysis of sugarcane bagasse. This work differs from the instant application, and it neither anticipates nor suggests the present invention, particularly due to being solely restricted to thermal optimization within the distillery for the purpose of increasing the amount of surplus bagasse from the first generation process. Furthermore, the said article also fails to consider the reuse of effluents and the thermal integration between the first and second generation processes for the production of ethanol, as claimed in the instant application.
The article with the title “Improving bioethanol production from sugarcane: evaluation of distillation, thermal integration and cogeneration systems” (Dias et al., Energy, 2011, 36(6): 3691-3703) discloses a study of energy optimization of a sugarcane plant (1st generation) by means of use of specific thermal integration for the distillation process, combined with the use of electric power cogeneration using the BIGCC—“Biomass Integrated Gasification Combined Cycle”—technology. This document neither anticipates nor suggests the system and method for energy integration of the technologies for the production of first and second generation ethanol as proposed herein, since it does not take into consideration the process for the production of cellulosic ethanol as constituting an alternative for the use of the biomass and it does not contemplate any solutions for reuse of effluents.
In patent application No. [BR] PI 0708266-5 A2 there are described a system and a method for the production of alcohol by distillation with energy optimization using the multiple effect technology. In this process, the feed to the distillation columns is split into two streams and fed to two sets of columns, one of these being a high pressure column and the other being a low pressure column, together with a reboiler which uses the thermal energy derived from the top of one column to supply heat to the other. This process demonstrates that when the system is adequately configured, it is possible to recover the heat available at the top of rectifying column B, however it does not indicate any applications external to the distillery. The present invention differs from this cited application on disclosing the use of streams available in the distillery, for example, in an associated second-generation ethanol production plant, applying the concept of integration of processes.
In patent application No. [BR] PI 0503931-2 A there is described an arrangement and a method for the production of anhydrous alcohol by way of a process of “Pressure Swing Adsorption” with energy optimization. In this process, a part of the heat contained in the end product (Anhydrous Alcohol) is recovered by means of thermal integration and mechanical compression of the anhydrous alcohol vapor, evidencing that when the process is configured in a well-structured manner, the recovery of the heat available in a stream with alcohol vapors is feasible. Application No. [BR] PI 0503931-2 A differs from the present invention in the fact that it discusses the application of the heat recovery technique in a specific manner for optimizing the consumption of vapor in the hydrated alcohol dehydration technology itself, however failing to discuss the thermal integration with any other process, and particularly with the technology for production of second generation ethanol.
In patent application No. US 2012/0041186 A1 there are described a method and a system for continuous pre-extraction of hemicellulose by vapor explosion treatment. In the said document, the “flash” stream has great energy potential for use in thermal recovery systems, although the cited document makes no mention to such applications. The present invention differs from the mentioned document due to using available and adequate streams from associated technologies/plants or in different sectors of the same process, in an integrated process concept.
In international publication No. WO 2012/021950 there is described a method for obtainment of an end stream of hydrolyzed product with high sugar content. The hydrolysis reaction system achieves its best efficiency level when the reaction temperature remains around 50° C. This characteristic of the hydrolysis system entails the need of a heat source in order to maintain the system at the specified temperature. However, the cited document does not suggest any specific strategy, arrangement, system and configuration for obtainment of the necessary energy to heat and maintain the optimum temperature in the hydrolysis system. The present invention differs from the said document in that it utilizes the streams/effluents generated in the conventional ethanol production process (irrespective of the raw material used in such process) to supply the energy required to heat the hydrolysis reactors and/or other equipment units of the 2G-ethanol plant.
In patent application No. [BR] PI 1101295-1, which applicant is Centro de Tecnologia Canavieira (CTC), there is described the use of vinasse (stillage) (raw, filtered, concentrated, etc.) and/or of any residue derived from the process of distillation of fermented wine as an alternative buffering agent in the process of enzymatic hydrolysis of lignocellulosic biomasses. The reuse of this and other effluents available in the conventional 1G-ethanol plants in combination with the present invention enhances the benefits that can be derived from the integrated process described in the present specification.
In patent application No. [BR] PI 0904538-4, filed by Centro de Tecnologia Canavieira (CTC), there is disclosed a process for optimizing the treatment of the plant biomass for the production of carbohydrates, ethanol and similar products, with the adoption of a process configuration which minimizes the total energy requirements of the industrial unit, on comparison with techniques currently employed and already well known. The said document evidences a complementary characteristic with relation to the present invention although it does not anticipate the objects that are claimed herein.
Based on what is gathered from the literature having been researched, there are not known to exist any documents that might anticipate or suggest the teachings of the present invention, so therefore the solution proposed herein is novel and evidences inventive step over the prior art.